1. Field of the Invention
This invention relates to the formation of dispersions of carbon black for use in the production of foam insulating products, particularly polyurethane and polyisocyanurate foams.
2. Description of the Prior Art
The use of carbon black to reduce the aged k-factor and hence improve the insulation value of closed cell, rigid, polymer foams is disclosed in U.S. Pat. No. 4,795,763. This patent establishes that uniformly dispersed carbon black filler effects a significant permanent reduction in the aged k-factor of foams. A failure to properly disperse the carbon black and stabilize the dispersion can result in clogging of the foam production equipment and the production of foam wherein the carbon black is clustered at the foam cell struts or highly agglomerated in a portion of the cell walls to yield little or no improvement in insulation value. It is accordingly highly desirable to find ways to simply and economically disperse carbon black in the ingredients employed in foam production and stabilize the dispersion, and thereafter form highly insulating foams from the dispersed mixture.